Module: RbNaCl::Util

Extended by:
Sodium
Defined in:
lib/rbnacl/util.rb

Overview

Various utility functions

Class Method Summary collapse

Methods included from Sodium

primitive, sodium_constant, sodium_function, sodium_function_with_return_code, sodium_primitive, sodium_type

Class Method Details

.bin2hex(bytes) ⇒ String

Hex encodes a message

Parameters:

  • bytes (String) —

    The bytes to encode

Returns:

  • (String) —

    Tasty, tasty hexadecimal



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# File 'lib/rbnacl/util.rb', line 278

def bin2hex(bytes)
  bytes.to_s.unpack1("H*")
end

.check_hmac_key(string, description) ⇒ Object

Check a passed in string, convertion if necessary

This method will check the key, and raise error if argument is not a string, and if it's empty string.

RFC 2104 HMAC The key for HMAC can be of any length (keys longer than B bytes are first hashed using H). However, less than L bytes is strongly discouraged as it would decrease the security strength of the function. Keys longer than L bytes are acceptable but the extra length would not significantly increase the function strength. (A longer key may be advisable if the randomness of the key is considered weak.)

see https://tools.ietf.org/html/rfc2104#section-3

Parameters:

  • string (#to_str) —

    The input string

  • description (String) —

    Description of the string (used in the error)

Raises:

  • (ArgumentError) —

    If we cannot convert to a string with #to_str

  • (RbNaCl::LengthError) —

    If the string is empty



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# File 'lib/rbnacl/util.rb', line 141

def check_hmac_key(string, description)
  check_string_validation(string)

  string = string.to_str

  if string.bytesize.zero?
    raise LengthError,
          "#{description} was #{string.bytesize} bytes (Expected more than 0)",
          caller
  end

  string
end

.check_length(string, length, description) ⇒ Object

Check the length of the passed in string

In several places through the codebase we have to be VERY strict with what length of string we accept. This method supports that.

Parameters:

  • string (String) —

    The string to compare

  • length (Integer) —

    The desired length

  • description (String) —

    Description of the string (used in the error)

Raises:



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# File 'lib/rbnacl/util.rb', line 83

def check_length(string, length, description)
  if string.nil?
    # code below is runs only in test cases
    # nil can't be converted to str with #to_str method
    raise LengthError,
          "#{description} was nil (Expected #{length.to_int})",
          caller
  end

  if string.bytesize != length.to_int
    raise LengthError,
          "#{description} was #{string.bytesize} bytes (Expected #{length.to_int})",
          caller
  end
  true
end

.check_string(string, length, description) ⇒ Object

Check a passed in string, converting the argument if necessary

In several places through the codebase we have to be VERY strict with the strings we accept. This method supports that.

Parameters:

  • string (#to_str) —

    The input string

  • length (Integer) —

    The only acceptable length of the string

  • description (String) —

    Description of the string (used in the error)

Raises:

  • (ArgumentError) —

    If we cannot convert to a string with #to_str

  • (RbNaCl::LengthError) —

    If the string is not the right length



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# File 'lib/rbnacl/util.rb', line 111

def check_string(string, length, description)
  check_string_validation(string)
  string = string.to_s
  check_length(string, length, description)

  string
end

.check_string_validation(string) ⇒ Object

Check a passed string is it valid

Raise an error if passed argument is invalid

Parameters:

  • string (#to_str) —

    The input string

Raises:

  • (TypeError) —

    If string cannot convert to a string with #to_str

  • (EncodingError) —

    If string have wrong encoding



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# File 'lib/rbnacl/util.rb', line 163

def check_string_validation(string)
  raise TypeError, "can't convert #{string.class} into String with #to_str" unless string.respond_to? :to_str

  string = string.to_str

  raise EncodingError, "strings must use BINARY encoding (got #{string.encoding})" if string.encoding != Encoding::BINARY
end

.hex2bin(hex) ⇒ String

Hex decodes a message

Parameters:

  • hex (String) —

    hex to decode.

Returns:

  • (String) —

    crisp and clean bytes



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# File 'lib/rbnacl/util.rb', line 287

def hex2bin(hex)
  [hex.to_s].pack("H*")
end

.prepend_zeros(n, message) ⇒ String

Prepends a message with zeros

Many functions require a string with some zeros prepended.

Parameters:

  • n (Integer) —

    The number of zeros to prepend

  • message (String) —

    The string to be prepended

Returns:

  • (String) —

    a bunch of zeros



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# File 'lib/rbnacl/util.rb', line 37

def prepend_zeros(n, message)
  zeros(n) + message
end

.remove_zeros(n, message) ⇒ String

Remove zeros from the start of a message

Many functions require a string with some zeros prepended, then need them removing after. Note: this modifies the passed in string

Parameters:

  • n (Integer) —

    The number of zeros to remove

  • message (String) —

    The string to be slice

Returns:

  • (String) —

    less a bunch of zeros



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# File 'lib/rbnacl/util.rb', line 50

def remove_zeros(n, message)
  message.slice!(n, message.bytesize - n)
end

.verify16(one, two) ⇒ Boolean

Compare two 16 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as OneTime#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?



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# File 'lib/rbnacl/util.rb', line 249

def verify16(one, two)
  return false unless two.bytesize == 16 && one.bytesize == 16

  c_verify16(one, two)
end

.verify16!(one, two) ⇒ Boolean

Compare two 16 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as OneTime#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?

Raises:

  • (ArgumentError) —

    If the strings are not equal in length



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# File 'lib/rbnacl/util.rb', line 267

def verify16!(one, two)
  check_length(one, 16, "First message")
  check_length(two, 16, "Second message")
  c_verify16(one, two)
end

.verify32(one, two) ⇒ Boolean

Compare two 32 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as HmacSha256#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?



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# File 'lib/rbnacl/util.rb', line 215

def verify32(one, two)
  return false unless two.bytesize == 32 && one.bytesize == 32

  c_verify32(one, two)
end

.verify32!(one, two) ⇒ Boolean

Compare two 32 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as HmacSha256#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?

Raises:

  • (ArgumentError) —

    If the strings are not equal in length



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# File 'lib/rbnacl/util.rb', line 233

def verify32!(one, two)
  check_length(one, 32, "First message")
  check_length(two, 32, "Second message")
  c_verify32(one, two)
end

.verify64(one, two) ⇒ Boolean

Compare two 64 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as HmacSha512#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?



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# File 'lib/rbnacl/util.rb', line 181

def verify64(one, two)
  return false unless two.bytesize == 64 && one.bytesize == 64

  c_verify64(one, two)
end

.verify64!(one, two) ⇒ Boolean

Compare two 64 byte strings in constant time

This should help to avoid timing attacks for string comparisons in your application. Note that many of the functions (such as HmacSha512#verify) use this method under the hood already.

Parameters:

  • one (String) —

    String #1

  • two (String) —

    String #2

Returns:

  • (Boolean) —

    Well, are they equal?

Raises:

  • (ArgumentError) —

    If the strings are not equal in length



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# File 'lib/rbnacl/util.rb', line 199

def verify64!(one, two)
  check_length(one, 64, "First message")
  check_length(two, 64, "Second message")
  c_verify64(one, two)
end

.zero_pad(n, message) ⇒ String

Pad a string out to n characters with zeros

Parameters:

  • n (Integer) —

    The length of the resulting string

  • message (String) —

    the message to be padded

Returns:

  • (String) —

    A string, n bytes long

Raises:



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# File 'lib/rbnacl/util.rb', line 62

def zero_pad(n, message)
  len = message.bytesize
  if len == n
    message
  elsif len > n
    raise LengthError, "String too long for zero-padding to #{n} bytes"
  else
    message + zeros(n - len)
  end
end

.zeros(n = 32) ⇒ String

Returns a string of n zeros

Lots of the functions require us to create strings to pass into functions of a specified size.

Parameters:

  • n (Integer) (defaults to: 32) —

    the size of the string to make

Returns:

  • (String) —

    A nice collection of zeros



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# File 'lib/rbnacl/util.rb', line 22

def zeros(n = 32)
  zeros = "\0" * n
  # make sure they're 8-bit zeros, not 7-bit zeros.  Otherwise we might get
  # encoding errors later
  zeros.respond_to?(:force_encoding) ? zeros.force_encoding("ASCII-8BIT") : zeros
end